libvirt/tests/securityselinuxhelper.c

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/*
* Copyright (C) 2011-2013 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
*/
#include <config.h>
/* This file is only compiled on Linux, and only if xattr support was
* detected. */
#include <dlfcn.h>
#include <errno.h>
#if HAVE_LINUX_MAGIC_H
# include <linux/magic.h>
#endif
#include <selinux/selinux.h>
#if HAVE_SELINUX_LABEL_H
# include <selinux/label.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/vfs.h>
#include <unistd.h>
#include <attr/xattr.h>
#ifndef NFS_SUPER_MAGIC
# define NFS_SUPER_MAGIC 0x6969
#endif
#define VIR_FROM_THIS VIR_FROM_NONE
#include "viralloc.h"
#include "virstring.h"
static int (*realstatfs)(const char *path, struct statfs *buf);
static int (*realsecurity_get_boolean_active)(const char *name);
static int (*realis_selinux_enabled)(void);
static const char *(*realselinux_virtual_domain_context_path)(void);
static const char *(*realselinux_virtual_image_context_path)(void);
#ifdef HAVE_SELINUX_LXC_CONTEXTS_PATH
static const char *(*realselinux_lxc_contexts_path)(void);
#endif
#if HAVE_SELINUX_LABEL_H
static struct selabel_handle *(*realselabel_open)(unsigned int backend,
struct selinux_opt *opts,
unsigned nopts);
static void (*realselabel_close)(struct selabel_handle *handle);
static int (*realselabel_lookup_raw)(struct selabel_handle *handle,
security_context_t *con,
const char *key,
int type);
#endif
static void init_syms(void)
{
if (realstatfs)
return;
#define LOAD_SYM(name) \
do { \
if (!(real ## name = dlsym(RTLD_NEXT, #name))) { \
fprintf(stderr, "Cannot find real '%s' symbol\n", #name); \
abort(); \
} \
} while (0)
LOAD_SYM(statfs);
LOAD_SYM(security_get_boolean_active);
LOAD_SYM(is_selinux_enabled);
LOAD_SYM(selinux_virtual_domain_context_path);
LOAD_SYM(selinux_virtual_image_context_path);
#ifdef HAVE_SELINUX_LXC_CONTEXTS_PATH
LOAD_SYM(selinux_lxc_contexts_path);
#endif
#if HAVE_SELINUX_LABEL_H
LOAD_SYM(selabel_open);
LOAD_SYM(selabel_close);
LOAD_SYM(selabel_lookup_raw);
#endif
#undef LOAD_SYM
}
/*
* The kernel policy will not allow us to arbitrarily change
* test process context. This helper is used as an LD_PRELOAD
* so that the libvirt code /thinks/ it is changing/reading
* the process context, whereas in fact we're faking it all.
* Furthermore, we fake out that we are using an nfs subdirectory,
* where we control whether selinux is enforcing and whether
* the virt_use_nfs bool is set.
*/
int getcon_raw(security_context_t *context)
{
if (!is_selinux_enabled()) {
errno = EINVAL;
return -1;
}
if (getenv("FAKE_SELINUX_CONTEXT") == NULL) {
*context = NULL;
errno = EINVAL;
return -1;
}
return VIR_STRDUP_QUIET(*context, getenv("FAKE_SELINUX_CONTEXT"));
}
int getcon(security_context_t *context)
{
return getcon_raw(context);
}
int getpidcon_raw(pid_t pid, security_context_t *context)
{
if (!is_selinux_enabled()) {
errno = EINVAL;
return -1;
}
if (pid != getpid()) {
*context = NULL;
errno = ESRCH;
return -1;
}
if (getenv("FAKE_SELINUX_CONTEXT") == NULL) {
*context = NULL;
errno = EINVAL;
return -1;
}
return VIR_STRDUP_QUIET(*context, getenv("FAKE_SELINUX_CONTEXT"));
}
int getpidcon(pid_t pid, security_context_t *context)
{
return getpidcon_raw(pid, context);
}
int setcon_raw(security_context_t context)
{
if (!is_selinux_enabled()) {
errno = EINVAL;
return -1;
}
return setenv("FAKE_SELINUX_CONTEXT", context, 1);
}
int setcon(security_context_t context)
{
return setcon_raw(context);
}
int setfilecon_raw(const char *path, security_context_t con)
{
const char *constr = con;
if (STRPREFIX(path, abs_builddir "/securityselinuxlabeldata/nfs/")) {
errno = EOPNOTSUPP;
return -1;
}
return setxattr(path, "user.libvirt.selinux",
constr, strlen(constr), 0);
}
int setfilecon(const char *path, security_context_t con)
{
return setfilecon_raw(path, con);
}
int getfilecon_raw(const char *path, security_context_t *con)
{
char *constr = NULL;
ssize_t len = getxattr(path, "user.libvirt.selinux",
NULL, 0);
if (STRPREFIX(path, abs_builddir "/securityselinuxlabeldata/nfs/")) {
errno = EOPNOTSUPP;
return -1;
}
if (len < 0)
return -1;
if (!(constr = malloc(len+1)))
return -1;
memset(constr, 0, len);
if (getxattr(path, "user.libvirt.selinux", constr, len) < 0) {
free(constr);
return -1;
}
*con = constr;
constr[len] = '\0';
return 0;
}
int getfilecon(const char *path, security_context_t *con)
{
return getfilecon_raw(path, con);
}
int statfs(const char *path, struct statfs *buf)
{
int ret;
init_syms();
ret = realstatfs(path, buf);
if (!ret && STREQ(path, abs_builddir "/securityselinuxlabeldata/nfs"))
buf->f_type = NFS_SUPER_MAGIC;
return ret;
}
int is_selinux_enabled(void)
{
return getenv("FAKE_SELINUX_DISABLED") == NULL;
}
int security_disable(void)
{
if (!is_selinux_enabled()) {
errno = ENOENT;
return -1;
}
return setenv("FAKE_SELINUX_DISABLED", "1", 1);
}
int security_getenforce(void)
{
if (!is_selinux_enabled()) {
errno = ENOENT;
return -1;
}
/* For the purpose of our test, we are enforcing. */
return 1;
}
int security_get_boolean_active(const char *name)
{
if (!is_selinux_enabled()) {
errno = ENOENT;
return -1;
}
/* For the purpose of our test, nfs is not permitted. */
if (STREQ(name, "virt_use_nfs"))
return 0;
init_syms();
return realsecurity_get_boolean_active(name);
}
const char *selinux_virtual_domain_context_path(void)
{
init_syms();
if (realis_selinux_enabled())
return realselinux_virtual_domain_context_path();
return abs_srcdir "/securityselinuxhelperdata/virtual_domain_context";
}
const char *selinux_virtual_image_context_path(void)
{
init_syms();
if (realis_selinux_enabled())
return realselinux_virtual_image_context_path();
return abs_srcdir "/securityselinuxhelperdata/virtual_image_context";
}
#ifdef HAVE_SELINUX_LXC_CONTEXTS_PATH
const char *selinux_lxc_contexts_path(void)
{
init_syms();
if (realis_selinux_enabled())
return realselinux_lxc_contexts_path();
return abs_srcdir "/securityselinuxhelperdata/lxc_contexts";
}
#endif
#if HAVE_SELINUX_LABEL_H
struct selabel_handle *selabel_open(unsigned int backend,
struct selinux_opt *opts,
unsigned nopts)
{
char *fake_handle;
init_syms();
if (realis_selinux_enabled())
return realselabel_open(backend, opts, nopts);
/* struct selabel_handle is opaque; fake it */
if (VIR_ALLOC(fake_handle) < 0)
return NULL;
return (struct selabel_handle *)fake_handle;
}
void selabel_close(struct selabel_handle *handle)
{
init_syms();
if (realis_selinux_enabled())
return realselabel_close(handle);
VIR_FREE(handle);
}
int selabel_lookup_raw(struct selabel_handle *handle,
security_context_t *con,
const char *key,
int type)
{
init_syms();
if (realis_selinux_enabled())
return realselabel_lookup_raw(handle, con, key, type);
/* Unimplemented */
errno = ENOENT;
return -1;
}
#endif